Heating tubes are used for example in the semiconductor industry to deposit thin films. Materials are vaporized in the heating tube, and the vapor is passed through an opening before depositing on a substrate. For example, triazines such as melamine may be vaporized, and the vapor, after passing through an opening, deposited on a substrate for coating. The heating tube must occasionally be cooled down, for example to replace the coating material (e.g. melamine), because it becomes depleted after being used to coat a number of substrates. The overall rate of production can be influenced by various operation times, particularly the time required to cool down the heating tube. Thus, a problem associated with heating tubes as they are used in coating applications is the time required for cooling down, with rapid cooling times being more desirable.
Although liquid water can be used in some circumstances as a coolant of hot apparatuses, the efficacy of water due in part to its high specific heat capacity and/or heat of vaporization, there are circumstances when using liquid water to cool items causes significant problems. For example, when temperatures are greater than the boiling temperature of water, its use as a coolant in a heat exchanger may cause high pressures, due to rapid vaporization of the water. High pressures may rupture gaskets and seals, and lead to failure of the heat exchanger.
There is a strong desire for a heat exchanger, particularly for use in cooling a heating tube or evaporator, which can increase the cooling rate, thereby increasing the productivity of the heating tube.
In view of the above, it is an object of the present invention to provide a heat exchanger that overcomes at least some of the problems in the art.